1. Field of the Invention
The present invention relates to a mobile communication system and a gateway selecting method thereof, and in particular, those in which when a mobile terminal connects to a predetermined connection network, a format conversion suitable to the mobile terminal is performed in a gateway.
2. Description of the Related Art
Recently, accompanied with the progress of mobile computing systems, services for obtaining contents on the Internet by using a mobile terminal or device have been provided.
In such an Internet access service in a mobile communication environment, the transmission speed of the relevant wireless-access line and the limitation in the resources of the mobile terminal (such as the display size or the memory capacity) should be considered, and thus in a gateway for connecting the mobile network and the Internet, the format of the original contents may be converted into a format suitable for the relevant mobile environment.
However, in conventional mobile communication systems, when the traffic of the Internet access from mobile terminals suddenly increases, the load imposed on each gateway for converting the format extremely increases, thereby causing inconvenience.
Here, each gateway for connecting a mobile network to the Internet performs a format conversion of the original contents so as to obtain a format suitable for the relevant mobile environment. Therefore, if the traffic of the Internet access from mobile terminals suddenly increases, and the load is concentrated on a specific gateway, the conversion process cannot be executed in time, that is, operation delay may occur, or in the worst case, some jobs cannot be processed.
Accordingly, gateway selecting methods for preventing such a concentration of the load on a specific gateway have been proposed. The following is an article which discloses an example of it: K. Yakura et al., “the Select Method of Plural Network for PDC Packet Mobile Communication Network”, Proceedings of the 1998 IEICE Communication Society Conference, B-5-87, p.337, 1998. In the disclosed method, the load is distributed by cyclically selecting one of several gateways (i.e., equal control). However, even in this method, the load may still be concentrated to a specific gateway because each subscriber has a different session opening time, and obtains a different amount of contents.